YOU SAID:
I saw ice cream squashed on car rooftop
INTO JAPANESE
私は車の屋上で砕いたアイスクリームを見た
BACK INTO ENGLISH
I saw crushed ice cream on the roof of the car
INTO JAPANESE
私は車の屋根に砕いたアイスクリームを見た
BACK INTO ENGLISH
I saw crushed ice cream on the roof of the car
That didn't even make that much sense in English.